Version history

To find out how to migrate your application from a previous version of APScheduler, see the migration section.


  • Fixed incorrect module name being generated for references to class methods via a subclass where the subclass does not override the method


  • Fixed TypeError related to entry point iteration on Python 3.9 (PR by CrypticDriver)


  • Ensured consistent support for both PySide and PyQt (v6 to v2) on QtScheduler
  • Replaced uses of the deprecated pkg_resources module with importlib.metadata (PR by Ran Benita)
  • Fixed scheduling class methods like B.methodname where the B class inherits from class A and methodname is a class method of class A
  • Fixed scheduler sleeping for too long (and thus jobs missing their scheduled run times) if its wakeup cycle takes too much time (fix by kbasten)


  • Fixed TypeError: arguments did not match any overloaded call: in QtScheduler due to wait_time being float and not an integer which QT needs it to be


  • Fixed compatibility with SQLAlchemy 2.0 and bumped minimum supported version to 1.4
  • Dropped support for Python versions older than 3.6


  • Removed a leftover check for pytz localize() and normalize() methods


  • Added support for PySide6 to the Qt scheduler
  • No longer enforce pytz time zones (support for others is experimental in the 3.x series)
  • Fixed compatibility with PyMongo 4
  • Fixed pytz deprecation warnings
  • Fixed RuntimeError when shutting down the scheduler from a scheduled job


  • Allowed the use of tzlocal v4.0+ in addition to v2.*


  • Allowed passing through keyword arguments to the underlying stdlib executors in the thread/process pool executors (PR by Albert Xu)


  • Dropped support for Python 3.4
  • Added PySide2 support (PR by Abdulla Ibrahim)
  • Pinned tzlocal to a version compatible with pytz
  • Ensured that jitter is always non-negative to prevent triggers from firing more often than intended
  • Changed AsyncIOScheduler to obtain the event loop in start() instead of __init__(), to prevent situations where the scheduler won’t run because it’s using a different event loop than then one currently running
  • Made it possible to create weak references to Job instances
  • Made the schedulers explicitly raise a descriptive TypeError when serialization is attempted
  • Fixed Zookeeper job store using backslashes instead of forward slashes for paths on Windows (PR by Laurel-rao)
  • Fixed deprecation warnings on the MongoDB job store and increased the minimum PyMongo version to 3.0
  • Fixed BlockingScheduler and BackgroundScheduler shutdown hanging after the user has erroneously tried to start it twice
  • Fixed memory leak when coroutine jobs raise exceptions (due to reference cycles in tracebacks)
  • Fixed inability to schedule wrapped functions with extra arguments when the wrapped function cannot accept them but the wrapper can (original PR by Egor Malykh)
  • Fixed potential where clause error in the SQLAlchemy job store when a subclass uses more than one search condition
  • Fixed a problem where bound methods added as jobs via textual references were called with an unwanted extra self argument (PR by Pengjie Song)
  • Fixed BrokenPoolError in ProcessPoolExecutor so that it will automatically replace the broken pool with a fresh instance


  • Fixed Python 2.7 accidentally depending on the trollius package (regression from v3.6.2)


  • Fixed handling of partial() wrapped coroutine functions in AsyncIOExecutor and TornadoExecutor (PR by shipmints)


  • Fixed OverflowError on Qt scheduler when the wait time is very long
  • Fixed methods inherited from base class could not be executed by processpool executor (PR by Yang Jian)


  • Adapted RedisJobStore to v3.0 of the redis library
  • Adapted RethinkDBJobStore to v2.4 of the rethink library
  • Fixed DeprecationWarnings about on Python 3.7 (PR by Roman Levin)


  • Fixed regression introduced in 3.5.2: Class methods were mistaken for instance methods and thus were broken during serialization
  • Fixed callable name detection for methods in old style classes


  • Fixed scheduling of bound methods on persistent job stores (the workaround of scheduling YourClass.methodname along with an explicit self argument is no longer necessary as this is now done automatically for you)
  • Added the FAQ section to the docs
  • Made BaseScheduler.start() raise a RuntimeError if running under uWSGI with threads disabled


  • Fixed OverflowError on Windows when the wait time is too long
  • Fixed CronTrigger sometimes producing fire times beyond end_date when jitter is enabled (thanks to gilbsgilbs for the tests)
  • Fixed ISO 8601 UTC offset information being silently discarded from string formatted datetimes by adding support for parsing them


  • Added the engine_options option to SQLAlchemyJobStore
  • Added the jitter options to IntervalTrigger and CronTrigger (thanks to gilbsgilbs)
  • Added combining triggers (AndTrigger and OrTrigger)
  • Added better validation for the steps and ranges of different expressions in CronTrigger
  • Added support for named months (jandec) in CronTrigger month expressions
  • Added support for creating a CronTrigger from a crontab expression
  • Allowed spaces around commas in CronTrigger fields
  • Fixed memory leak due to a cyclic reference when jobs raise exceptions (thanks to gilbsgilbs for help on solving this)
  • Fixed passing wait=True to AsyncIOScheduler.shutdown() (although it doesn’t do much)
  • Cancel all pending futures when AsyncIOExecutor is shut down


  • Dropped support for Python 3.3
  • Added the ability to specify the table schema for SQLAlchemyJobStore (thanks to Meir Tseitlin)
  • Added a workaround for the ImportError when used with PyInstaller and the likes (caused by the missing packaging metadata when APScheduler is packaged with these tools)


  • Fixed Python 2.7 compatibility in TornadoExecutor


  • The asyncio and Tornado schedulers can now run jobs targeting coroutine functions (requires Python 3.5; only native coroutines (async def) are supported)
  • The Tornado scheduler now uses TornadoExecutor as its default executor (see above as for why)
  • Added ZooKeeper job store (thanks to Jose Ignacio Villar for the patch)
  • Fixed job store failure (get_due_jobs()) causing the scheduler main loop to exit (it now waits a configurable number of seconds before retrying)
  • Fixed @scheduled_job not working when serialization is required (persistent job stores and ProcessPoolScheduler)
  • Improved import logic in ref_to_obj() to avoid errors in cases where traversing the path with getattr() would not work (thanks to Jarek Glowacki for the patch)
  • Fixed CronTrigger’s weekday position expressions failing on Python 3
  • Fixed CronTrigger’s range expressions sometimes allowing values outside the given range


  • Added the ability to pause and unpause the scheduler
  • Fixed pickling problems with persistent jobs when upgrading from 3.0.x
  • Fixed AttributeError when importing apscheduler with setuptools < 11.0
  • Fixed some events missing from and
  • Fixed wrong run time being set for date trigger when the timezone isn’t the same as the local one
  • Fixed builtin id() erroneously used in MongoDBJobStore’s JobLookupError()
  • Fixed endless loop with CronTrigger that may occur when the computer’s clock resolution is too
    low (thanks to Jinping Bai for the patch)


  • Added RethinkDB job store (contributed by Allen Sanabria)
  • Added method chaining to the modify_job(), reschedule_job(), pause_job() and
    resume_job() methods in BaseScheduler and the corresponding methods in the Job class
  • Added the EVENT_JOB_SUBMITTED event that indicates a job has been submitted to its executor.
  • Added the EVENT_JOB_MAX_INSTANCES event that indicates a job’s execution was skipped due to its maximum number of concurrently running instances being reached
  • Added the time zone to the repr() output of CronTrigger and IntervalTrigger
  • Fixed rare race condition on scheduler shutdown()
  • Dropped official support for CPython 2.6 and 3.2 and PyPy3
  • Moved the connection logic in database backed job stores to the start() method
  • Migrated to setuptools_scm for versioning
  • Deprecated the various version related variables in the apscheduler module (apscheduler.version_info, apscheduler.version, apscheduler.release, apscheduler.__version__)


  • Fixed bug in the cron trigger that produced off-by-1-hour datetimes when crossing the daylight saving threshold (thanks to Tim Strazny for reporting)


  • Fixed cron trigger always coalescing missed run times into a single run time (contributed by Chao Liu)
  • Fixed infinite loop in the cron trigger when an out-of-bounds value was given in an expression
  • Fixed debug logging displaying the next wakeup time in the UTC timezone instead of the scheduler’s configured timezone
  • Allowed unicode function references in Python 2


  • Fixed memory leak in the base executor class (contributed by Stefan Nordhausen)


  • Fixed compatibility with pymongo 3.0


  • Fixed ValueError when the target callable has a default keyword argument that wasn’t overridden
  • Fixed wrong job sort order in some job stores
  • Fixed exception when loading all jobs from the redis job store when there are paused jobs in it
  • Fixed AttributeError when printing a job list when there were pending jobs
  • Added setuptools as an explicit requirement in install requirements


  • A wider variety of target callables can now be scheduled so that the jobs are still serializable (static methods on Python 3.3+, unbound methods on all except Python 3.2)
  • Attempting to serialize a non-serializable Job now raises a helpful exception during serialization. Thanks to Jeremy Morgan for pointing this out.
  • Fixed table creation with SQLAlchemyJobStore on MySQL/InnoDB
  • Fixed start date getting set too far in the future with a timezone different from the local one
  • Fixed _run_job_error() being called with the incorrect number of arguments in most executors


  • Added support for timezones (special thanks to Curtis Vogt for help with this one)
  • Split the old Scheduler class into BlockingScheduler and BackgroundScheduler and added integration for asyncio (PEP 3156), Gevent, Tornado, Twisted and Qt event loops
  • Overhauled the job store system for much better scalability
  • Added the ability to modify, reschedule, pause and resume jobs
  • Dropped the Shelve job store because it could not work with the new job store system
  • Dropped the max_runs option and run counting of jobs since it could not be implemented reliably
  • Adding jobs is now done exclusively through add_job() – the shortcuts to triggers were removed
  • Added the end_date parameter to cron and interval triggers
  • It is now possible to add a job directly to an executor without scheduling, by omitting the trigger argument
  • Replaced the thread pool with a pluggable executor system
  • Added support for running jobs in subprocesses (via the processpool executor)
  • Switched from nose to py.test for running unit tests


  • Added Redis job store
  • Added a “standalone” mode that runs the scheduler in the calling thread
  • Fixed disk synchronization in ShelveJobStore
  • Switched to PyPy 1.9 for PyPy compatibility testing
  • Dropped Python 2.4 support
  • Fixed SQLAlchemy 0.8 compatibility in SQLAlchemyJobStore
  • Various documentation improvements


  • The scheduler now closes the job store that is being removed, and all job stores on shutdown() by default
  • Added the last expression in the day field of CronTrigger (thanks rcaselli)
  • Raise a TypeError when fields with invalid names are passed to CronTrigger (thanks Christy O’Reilly)
  • Fixed the example by shutting down the scheduler on Ctrl+C
  • Added PyPy 1.8 and CPython 3.3 to the test suite
  • Dropped PyPy 1.4 - 1.5 and CPython 3.1 from the test suite
  • Updated setup.cfg for compatibility with distutils2/packaging
  • Examples, documentation sources and unit tests are now packaged in the source distribution


  • Removed the unique constraint from the “name” column in the SQLAlchemy job store
  • Fixed output from Scheduler.print_jobs() which did not previously output a line ending at the end


  • Fixed cron style jobs getting wrong default values


  • Added configurable job stores with several persistent back-ends (shelve, SQLAlchemy and MongoDB)
  • Added the possibility to listen for job events (execution, error, misfire, finish) on a scheduler
  • Added an optional start time for cron-style jobs
  • Added optional job execution coalescing for situations where several executions of the job are due
  • Added an option to limit the maximum number of concurrently executing instances of the job
  • Allowed configuration of misfire grace times on a per-job basis
  • Allowed jobs to be explicitly named
  • All triggers now accept dates in string form (YYYY-mm-dd HH:MM:SS)
  • Jobs are now run in a thread pool; you can either supply your own PEP 3148 compliant thread pool or let APScheduler create its own
  • Maximum run count can be configured for all jobs, not just those using interval-based scheduling
  • Fixed a v1.x design flaw that caused jobs to be executed twice when the scheduler thread was woken up while still within the allowable range of their previous execution time (issues #5, #7)
  • Changed defaults for cron-style jobs to be more intuitive – it will now default to all minimum values for fields lower than the least significant explicitly defined field


  • Fixed time difference calculation to take into account shifts to and from daylight saving time


  • Added __repr__() implementations to expressions, fields, triggers, and jobs to help with debugging
  • Added the dump_jobs method on Scheduler, which gives a helpful listing of all jobs scheduled on it
  • Fixed positional weekday (3th fri etc.) expressions not working except in some edge cases (fixes #2)
  • Removed autogenerated API documentation for modules which are not part of the public API, as it might confuse some users


Positional weekdays are now used with the day field, not weekday.


  • Fixed regression: add_cron_job() in Scheduler was creating a CronTrigger with the wrong parameters (fixes #1, #3)
  • Fixed: if the scheduler is restarted, clear the “stopped” flag to allow jobs to be scheduled again


  • Added the week option for cron schedules
  • Added the daemonic configuration option
  • Fixed a bug in cron expression lists that could cause valid firing times to be missed
  • Fixed unscheduling bound methods via unschedule_func()
  • Changed CronTrigger constructor argument names to match those in Scheduler


  • Fixed a corner case where the combination of hour and day_of_week parameters would cause incorrect timing for a cron trigger